Photosynthesis & Respiration

Objectives Recognize that most plants and animals require food and oxygen Identify the function of the chloroplast during photosynthesis Describe photosynthesis is a chemical change with reactants and products that takes place in the presence of light and chlorophyll

Describe how oxygen is needed by all cells of most organisms for the release of energy from nutrient molecules Describe the importance of the transport and exchange of oxygen and carbon dioxide to the survival of the organism Objectives

Two ways to get food “troph” = food Autotrophs –Auto = self –Autotrophs make their own food Heterotrophs –Hetero = different –Heterotrophs get their food from something else (they have to eat it)

Two ways to get food Autotrophs –Plants Heterotrophs –Animals

Photosynthesis

What is Photosynthesis? The process of photosynthesis is a chemical reaction. It is the most important chemical reaction on our planet.

What is the equation for the chemical reaction of photosynthesis?

Six molecules of carbon dioxide react with six molecules of water to form 1 molecule of glucose and six molecules of oxygen.

Photosynthesis Converts the sun’s energy into chemical energy stored in sugar Takes place in specialized structures inside plant cells called chloroplasts –Chlorophyll is the pigment that absorbs sunlight.

What happens during photosynthesis? Plants capture light energy and use that energy to make glucose Sunlight provides the energy needed by chlorophyll to change molecules of carbon dioxide and water into glucose Oxygen is also released in this reaction

What happens during photosynthesis? Carbon dioxide enters the leaf through holes called stomata CO 2 combines with the stored energy in the chloroplasts through a chemical reaction to make glucose The sugar is moved through tubes in the leaf to the roots, stems and fruits of the plants Some of the sugar is used right away by the plant for energy; some is stored as starch; and some is built into plant tissue

Why is this important to us? We cannot make our own food (glucose, energy), we must get our food from plants. Plants are the first step in the food chain.

Why is this important to us? The oxygen released during photosynthesis is necessary for all living things.

What is Cellular Respiration? The release of chemical energy for use by cells.

Cellular Respiration Happens in both plant and animal cells Overall Reaction: –C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O

What is Cellular Respiration? Once the energy that was in sunlight is changed into chemical energy by photosynthesis, an organism has to transform the chemical energy into a a form that can be used by the organism. photosynthesis This process is cellular respiration.

Cellular Respiration The process by which mitochondria break down glucose to make ATP In order for our bodies to use the energy, the food must be broken down into a usable form –What is the usable form of energy? –What type of process breaks down molecules?

Describe Cellular Respiration The breakdown of glucose molecules to release energy Takes place in all living things Is a step by step process

Cellular Respiration Overview Depends on whether or not there is oxygen Aero = oxygen Aerobic Respiration – makes energy Anaerobic Respiration – Fermentation (makes alcohol)

Step 1: Glycolysis The energy that cells make and use is called ATP –Adenosine triphosphate Glycolysis makes 2 molecules of ATP (energy) Glycolysis happens in the cytoplasm of the cell

Step 2: Check for Oxygen If oxygen is present, the cell can make more ATP If no oxygen is present, the cell has to recycle the pieces from glycolysis and makes alcohol.

Step 3 without oxygen: Fermentation The cell must recycle the materials from glycolysis. This recycling process is called fermentation. The product of fermentation is alcohol.